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When It's Time To Fight, Chameleon Shows True Colors

posted 15 Dec 2013, 05:43 by Mpelembe   [ updated 15 Dec 2013, 05:43 ]

The chameleon is best known for its ability to blend in with its surroundings by changing color, but a study by scientists at Arizona State University demonstrates that the lizard also uses color change to intimidate its rivals. According to behavioural ecologist Russell Ligon (pron: Liggon), the outcome of most chameleon fights can be predicted on the basis of color change and intensity in the lead up to combat.

TEMPEARIZONAUNITED STATES (RECENT) (RUSSELL LIGON) -  When two male Veiled chameleons (Chamaeleo calyptratus) confront one another, the stand-off triggers changes in color that behavioural ecologist Russell Ligon says, serve as reliable predictors of who will win the fight.

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In a study published in the online journal "Biology Letters', Ligon says little is known or understood about the communication function served by color change in animals like chameleons and cephalopods. In an effort to learn more, he and Arizona State university colleague Kevin McGraw staged and recorded several aggressive one-on-one encounters with random pairs from a group of ten male Veiled chameleons to establish how the lizards use color change in aggressive situations. The researchers measured color changes in relation to distance travelled by both lizards as they approached one another, and changes of color intensity from more than 20 points on each animal.

Ligon points out that during the course of their research, the scientists did "everything within our power to minimize the risks chameleons actually face during these interactions."

The experiments were revealing. When one male wants to fight, he'll turn side-on to his opponent and display his coloration in contrasting, yellow, lateral stripes, as a way to communicate his willingness to do battle, according to Ligon. As the lizards approach each other and their heads become more prominent to one another in their fields of vision, a second show of color is triggered. Ligon says he thinks the lizard's head coloration display serves as a final warning to the aggressor of its motivation to win the fight, before

actual combat begins. Ligon says the chameleon with the brighter head coloration usually wins the fight.

To the Veiled chameleon, Ligon says motivation to win as indicated by color change may be more important than strength in determining the outcome.

"Males that achieved brighter stripe coloration were more likely to approach their opponent, and those that attained brighter head coloration were more likely to win fights; speed of head color change was also an important predictor of contest outcome," said Ligon.

Different color change signals he says, may evolve to communicate different information, in this case, motivation and fighting ability. He says they may also be a determining factor in attracting a mate.

Ligon says the study is "the first to document the use of multiple, behaviourally accentuated color-change signals to communicate different information."